Device for introducing additives into molten metal

ABSTRACT

A device for introducing additives, such as solid substances of low boiling point, into a molten metal includes an intermediate ladle for receiving the molten metal and discharging it from an outlet opening in its base into an outlet pipe extending downwardly from the opening. A feed pipe for introducing additives extends downwardly through the ladle with its lower end located in the outlet opening from the ladle. The lower end of the feed pipe is spaced radially inwardly from the inner peripheral of the ladle outlet opening and provides an annular space which is divided by ribs, extending between the ladle and the lower end of the feed pipe, into a number of angularly spaced open sections or flow passages. The ribs extend downwardly for at least a portion of the length of the outlet pipe and the outlet pipe is arranged to provide, in serial arrangements proceeding from the outlet opening in the ladle, a converging section, a cylindrical section, and a diverging nozzle-like section.

O United States Patent [151 3,650,516 Mantel] et al. [4 1 Mar. 21, 1972[54] DEVICE FOR INTRODUCING 3,137,753 6/1964 Feichtinger ..75/34 TADDITIVES INTO MOLTEN METAL 3,356,489 12/ 1967 Feichtinger. ..75/933,357,692 12/1967 Bakkerusm, ..266/34 A [72] Inventors: Detmar FranzOtto Mantell; Werner garlalld Valentin Malnz, both of Gelsen- PrimaryExaminer Gera|d Dost Germany Attorney-McGlew & Toren [73] Assignee:Rheinstahl l-luettenwerke AG, Essen, Germany [57] ABSTRACT [22] Filed:Mar. 25, 1970 A device for introducing additives, such as solidsubstances of low boiling point, into a molten metal includes an inter-[2l 1 Appl' 22650 mediate ladle for receiving the molten metal anddischarging it from an outlet opening in its base into an outlet pipeextending [52] U.S. Cl ..266/34 T, 75/93, 164/57, downwardly from theopening. A feed pipe for introducing ad- 1 4/266, 66/34 A ditivesextends downwardly through the ladle with its lower [51] lnt.C| ..C2lc7/00 nd located in the outlet opening from the ladle. The lower FleldSearch 34 A, 34 end of the feed pipe is spaced radially inwardly fromthe inner 64/57, 266, 337', 75/53, 61, 9 12 130 A, 130 peripheral of theladle outlet opening and provides an annular 130 C; 222/145; 239/433 590space which is divided by ribs, extending between the ladle and thelower end of the feed pipe, into a number of angularly [56] Referencescued spaced open sections or flow passages, The ribs extend UNITEDSTATES PATENTS downwardly for at least a portion of the length of theoutlet pipe and the outlet plpe 18 arranged to provide, in serial ar-1,151,332 8/1915 Baggaley ..266/34 T rangemems ro eding from the outletopening in the ladle, a 2,291,221 7/1942 Glbson T converging section, acylindrical section, and a diverging noz- 2,302,999 11/1942 OBrien....266/34 T Z|e ]ike Section, 2,997,384 8/1961 Feichtinger ..75/932,997,386 8/1961 Feichtinger ..75/93 18 Claims, 4 Drawing FiguresPatented March 21, 1972 2 Sheets-Sheet 1 02mm mm: MW? (QERDER HMLD VBLNTW NMUZ B Y I W585i) MTM ATTOR D E Y S DEVICE FOR INTRODUCING ADDITIVESINTO MOLTEN METAL SUMMARY OF THE INVENTION The invention is directed toa device for introducing additives, in particular solid substanceshaving low boiling points, into molten metal and especially into molteniron. More particularly, the invention concerns the outlet arrangementof a feed pipe and the outlet opening from an intermediate ladle forintroducing the additives into the molten metal as it flows downwardlywithin an outlet pipe from the intermediate ladle.

The introduction of magnesium or other additives into molten iron forthe production of cast iron of a particular grade, such as cast ironwith spherical graphite, has been the object of numerous studies to finda satisfactory solution to the problem of introducing the additives.However, until the conception of the present invention it has not beenpossible to find a satisfactory method of introducing the additives intothe molten iron in a safe manner. Where magnesium has been used as theadditive it has been introduced in pure form as well as in the form ofmagnesium alloys of different compositions, usually in a lumpy or finegrained condition or in the form of immersion bodies, the treatmentinvolving the introduction of the additive often occurring by a fillingor immersion method. Furthermore, on occasion the magnesium has beenintroduced in gaseous form by using auxiliary gases or in a form of cokeimpregnated with magnesium and using the immersion method ofintroduction.

These various methods used in the past have a number of shortcomings. Inparticular the magnesium yield and the precision of the magnesiumtreatments usually have been unsatisfactory, the temperature lossesduring the treatment have often been too high, the duration of thetreatment has been undesirably long, and the introduction of theadditive frequently has required complicated manipulations.

In the German Auslegeschrift 1,278,457 an apparatus is disclosed inwhich the molten iron flows through a closed channel, into whichmagnesium in the form of wire or of tubes is fed through lateralapertures in such a way that the magnesium is melted by the molten iron.For an effective treatment using this apparatus the cross section of thechannel is determined in accordance with certain mathematical formula.In another embodiment of this construction, alloying agents in granularform are fed through a lateral aperture in a closed pipe through whichthe molten iron flows. In the course of numerous experiments it has beenfound, especially in a rapid treatment cycle, that there is no time forthorough cleaning of the closed reaction pipe between two treatmentcycles with the result that obstructions develop because of thesintering of the alloy in the feed pipe and also due to build up in thereaction pipe and as a consequence the treatments must be interruptedand a certain amount of waste is produced.

In German Pat. No. 1,433,594 a device is set forth in which a feed pipefor the additives passes coaxially through the outflow channel in thebottom of a storage chamber for the molten metal. The outflow channeltapers uniformly to its mouth and the lower edge of the feed pipeprojects below the mouth of the outflow channel. It is stated that inthis arrangement, under the action of the surface tension of the metal,in particular where cast iron is used, a closed hollow jet is developedwhich absorbs the vapor pressure of the magnesium added through the feedpipe without any breaks taking place in its surface. It is indicatedthat the reaction of the magnesium with the iron occurs in the interiorof the hollow jet and is completed before the freely falling laminar jetimpinges on the surface of the material contained in the basin below theoutflow channel. In this arrangement it is pointed out that an essentialfeature is the location of the lower edge of the feed pipe projectingfrom the mouth of the outflow channel as, without this arrangement,obstructions of the feed pipe will develop and explosions may take placewithin the device when magnesium is added. Experiments conducted on thedevice disclosed in the above German patent have shown that the surfacetension of the molten cast iron is not sufficiently reliable to avoidany breaks in the surface of the hollow jet. Further, small slagparticles, which inevitably are entrained in the mo]- ten metal, reducethe surface tension to such an extent that the jet surface breaks, themagnesium escapes as a vapor, and the magnesium treatment is notsuccessful. Slag intercepting devices have not provided a reliablesolution and have resulted in additional disadvantages in that residualiron collects in an inflow box and must be drained by complicatedmanipulations.

Therefore, it is the primary object of the present invention to avoidthe problems experienced in the past and to provide a device for theintroduction of additives in an absolutely reliable manner so that thedevice does not require any servicing for the elimination ofdisturbances even during shutdowns and the production of waste oroperational disturbances are avoided when the additive treatments takeplace in rapid succession. In accordance with the present invention, thepoints of introduction of the additive into the molten metal take placeat an outflow opening from an intermediate supply member in whichangularly spaced open sections are provided between the outlet openingfrom the supply vessel and the outer surface of the additive feed pipeby means of ribs which extend in the radial direction between the feedpipe and the outlet opening and an outlet pipe is arranged below theoutlet opening to receive the molten metal and additives with the ribsextending downwardly into the pipe from the outlet openmg.

By dividing the outlet opening from the supply vessel into a pluralityof open sections, flow apertures are provided for the molten metal as itenters into the outlet pipe. In this arrange ment the additivesintroduced through the feed pipe and the individual metal jets flowingthrough the open sections fall, at first, independently of each other tothe bottom. In this manner any splashing, which might take place, isshifted downwardly from the critical point, that is the inlet mouth tothe outlet pipe, and splashing which would obstruct the outlet from thefeed pipe is prevented. Furthermore, the possibility of any blockage inthe feed pipe caused by sintering is reliably avoided. Furthermore, inthis arrangement it is completely immaterial whether the surface tensionof the molten metal is temporarily reduced by entrained slag. Thearrangement of the downwardly extending outlet pipe directs the moltenmetal in such a manner that a turbulent flow results with intimatemixture with the additives so that the desired reaction between themolten metal and the additive is effected. Furthermore, the additive isdistributed in a completely uniform manner throughout the molten metal.In this arrangement the access of air is prevented and for easilyoxidizing additives, such as aluminum, a high yield is achieved. Inaddition, when magnesium is added, evaporation losses are kept to aminimum. Additional characteristics of the present invention, whichenhance its effectiveness include the downward extension of the ribswhich subdivide the annular space between the feed pipe and the supplyvessel outlet opening so that the molten metal is conducted downwardlyin a positive fashion and turbulent flow is assured. To produce thedesired flow characteristics the portion of the outlet pipe extendingdownwardly from the outlet opening in the supply vessel convergesinwardly for a portion of its length. The combination of the downwardlyextending ribs and the converging walls of the outlet pipe promote theintimate mixing of the metal and the additives. In the event anymagnesium vapors form, a sufficient volume is available so that they canrise without causing any back pressure on the molten metal.Additionally, the inner surface of the outlet pipe can be provided withelevations or depressions extending normally to its axis, and preferablysuch means are arranged in the converging zone of the outlet pipe.Another feature of the outlet pipe is the provision of a divergingnozzle-like section located below the converging zone with the possiblearrangement of a short cylindrical section between the two taperingzones. It has been found that it is advisable, especially in treatmentsutilizing magnesium, to provide the outlet pipe with multiplenozzle-like sections with their minimum cross sections decreasing fromthe top to bottom of the pipe.

Due to the design of the molten metal flow openings from the supplyvessel and the arrangement of the outlet pipe, the additives reactcompletely with the molten metal without any disturbance and, inaddition, the length of the outlet pipe can be kept relatively short.Therefore, the device has the additional advantage of a short structuralheight.

To prevent air from gaining access into the outlet pipe from its lowerend, the bottom of the outlet pipe can be terminated immediately abovethe bottom of a vessel or ladle into which the mixture of the moltenmetal and additive is being delivered so that the lower end of theoutlet pipe is closed immediately after the commencement of the flow ofthe molten metal downwardly into the lower ladle or vessel. For thispurpose, a bottom recess may be formed in the lower vessel.

In another preferred form of the invention, a telescoping refractorytube is provided on the lower end of the outlet pipe and the tube isguided for axial displacement along the outer surface of the outlet pipewith its upward movement aided by means of a refractory float located onthe lower exterior end of the tube.

In another embodiment of the invention, the outlet pipe can be closed atits lower end by providing a siphon type structure between the lower endof the outlet pipe and the vessel into which it delivers the moltenmetal and additive. A particular appropriate design of such anembodiment includes a tubular section formed in the wall of the vesselreceiving the molten metal from the outlet pipe with the tubular sectionextending downwardly from the lower end of the outlet pipe into a basinwhich surrounds its lower end. The molten metal flowing downwardlythrough the tubular section flows from the basin into the lower vesseland the upper edge of the basin is located at a higher level than thelower end of the tubular section. Especially when magnesium is beingintroduced, magnesium vapor may sometimes collect in the siphon typepart of the lower vessel. However, as a rule a sufficient volume isavailable because of the sufficiently large cross section of the tubularpart of the siphon portion.

Granular or pulverized additives are usually introduced by means of aproportioning funnel positioned at the upper end of the feed pipe. Atits lower end, vapors from the additives can get into the feed pipe andshould this occur to a disturbing extent, it is recommended to form thefeed pipe as a pair of concentrically arranged pipes, so that theproportioning funnel delivers the additive into the inner pipe while anyvapors can escape through the annular space formed between the inner andouter pipes. Additionally, in such an arrangement an additional funnelcan be disposed concentrically about the proportioning funnel with thesecond funnel being connected directly to the upper end of the innerpipe.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this specification. For a better understanding of the invention,its operating advantages and specific objects attained by its uses,reference should be had to the accompanying drawings and descriptivematter in which there are illustrated preferred embodiments of theinvention.

DESCRIPTION OF THE DRAWINGS the additive is introduced in rod form.

DETAILED DESCRIPTION OF THE INVENTION In FIG. 1 a device is illustratedwhich is intended, in particular, for the introduction of granular orpulverized substances, especially substances of low boiling point, intomolten iron and consists of a vertically arranged feed pipe I forintroducing the additives into the molten metal. The feed pipe extendsdownwardly into an outlet opening 2 of an intermediate supply vessel orladle which contains the molten metal. The lower end of the feed pipe 1terminates at the mouth of the outlet opening 2 and the outer surface ofthe lower end of the feed pipe is spaced inwardly from the juxtaposedsurface of the vessel 3 forming the outlet opening 2. A plurality ofannularly spaced open sections 4 are provided in the outlet opening 2from the vessel 3 by a plurality of ribs 5 which extend radially betweenthe outer wall of the lower end of the feed pipe 1 and the surfaceforming the outlet opening from the vessel 3. In FIG. 3 the arrangementsof the angularly spaced open sections 4 is indicated for discharging themolten metal from the vessel or ladle 3.

Positioned at and extending downwardly from the outlet opening 2 fromthe vessel 3 is an outlet pipe 6 which conducts the molten metal fromthe vessel and the additives from the feed pipe 1 in the downwarddirection. An inwardly converging zone 7 is provided in the outlet pipe6 from its connection to the outlet opening 2 downwardly for a part ofthe length of the pipe. As can be noted in FIG. 1, the ribs 5 extenddownwardly from the lower end of the feed pipe 1 through the outlet pipe6 for a part of its length with the ribs extending at least beyond theinwardly converging zone 7 of the pipe. Between the vertically extendingribs 5, projections or protuberances are formed on the inner surface ofthe outlet pipe 6 extending normal to the axis of the pipe. Theprojections or protuberances 8 are located in the inwardly convergingzone 7 of the outlet pipe.

Immediately below the converging zone 7 of the outlet pipe 6 a shortcylindrical section 9 is provided which is followed by a diverging zone10 widening in the downward direction in a nozzle-like form. Asindicated in FIG. 1 the lower ends of the ribs 5 terminate intermediatethe ends of the diverging zone 10 of the pipe. The outlet pipe 6 conveysthe molten metal and additives downwardly and delivers them into theupper end of another vessel or ladle l2. Formed as a part of one wall ofthe ladle 12 is a siphon type component 11 which forms a tubularpassageway into the lower portion of the ladle 12. At its upper end, thesiphon type component 11 receives the lower end of the outlet pipe 6 forconveying the mixture of molten metal and additives downwardly into abasin 13 formed in the bottom of the ladle 12 with the center of thebasin being offset from the tubular passageway through the siphon typecomponent 11. The lower end 15 of the tubular passageway through thesiphon type component 11 terminates at a level below the upper edge ofthe basin 13 so that the material is discharged from the tubularpassageway into the basin at a level below the edge of the basin overwhich the material flows into the main portion of the ladle 12.

In FIG. 1 a funnel 16 is positioned extending into the upper end of thefeed pipe 1 for introducing the additives into the feed pipe.

In FIG. 2 an alternate arrangement is shown for the feed pipe 1 in whichcoaxially arranged pipes are provided with an inner pipe 17 beingpositioned within a concentrically arranged outer pipe 18. At the upperend of the feed pipe arrangement the proportioning funnel 16 is spacedupwardly from the upper end of the inner pipe 17 and a concentricallyarranged funnel l9 encircles the proportioning funnel and is connectedat its lower end to the upper end of the inner pipe 17. The additivesintroduced through the funnel 16 pass downwardly through the inner pipe17 into the outlet pipe 6.

As an alternative to the arrangement shown in FIG. 3 a single refractoryunit can be constructed to form the open sections 4 which provide theoutlet apertures from the intermediate vessel 3. The single refractoryunit also incorporates the upper ends of the ribs 5 and the lower end ofthe feed pipe 1 in the zone of the outlet opening from the vessel 3.

The device described above has been used in treating a large number ofcharges of molten metal with magnesium and no disturbances whatever havebeen encountered. The charges of molten metal were quiet during'thetreatment and no smoke was developed.

The following are three examples of the results obtained using theabove-identified device.

The quantity of iron was 1,500 to 1,520 kg. The iron contained 3.8 to3.9 percent C, 0.20% Mn, 0.09% P. The flow time (treatment time) wasbetween 133 and 142 sec. To each charge of iron 20 kg. of a granularmagnesium alloy containing 5 percent Mg (grain size 1 to 4 mm.) wereadded. The results are compiled in the following table. Obviously themagnesium yield is very high and the temperature losses are outlet pipein which the converging zone 7, its cylindrical section 9 and divergingzone are repeated, at 7', 9' and 10', so that a pair of nozzle-likesections are provided within the length of the outlet pipe. In thearrangement in FIG. 4 the cross section of the cylindrical portion 9 inthe lower nozzle is less than in the upper nozzle section.

Due to the various measures provided by the above device for extensivesuppression of the evolution of vapors and for the removal of suchvapors it is possible to insure that no back pressure can develop on themolten metal within the outlet pipe 6 even when substances of a very lowboiling point are added, such as magnesium. With the construction of thedevice disclosed in FIG. 4 it has been determined that the magnesiumyield is approximately 65 percent and the temsatisfactorilylow. a vperature losses during the treatment are low.

Temp. Temp. Before treatment After treatment before 7 after treattreat-Yield of 81 S (10- S (10- Mg (10- ment merit ME in (percent) percent) Sipercent) percent) 0.) C percent In FIG. 4 an alternate arrangement ofthe present invention gg whil e s pecific embodiments of the inventionhave been is disclosed in which the additive substance is introduced inthe form of a rod material 28 and is conveyed downwardly through thefeed pipe 1 by means of a feed device 29. The outside diameter of therod material is less than the inside diameter of the feed pipe so thatany vapors which evolve can escape in the annular gap between the rodmaterial and the inside of the pipe. The arrangement of the feed pipe 1and the outlet opening 2 from the vessel 3 with the ribs 5 is similar tothat shown in FIG. I and the same reference numerals are employed.Further, the outlet pipe 6 extends downwardly from the outlet opening 2in the vessel 3 for conveying the mixture of the rod material and themolten metal downwardly into the vessel or ladle 12. At the lower end ofthe outlet pipe 6 a refractory-lined steel pipe 21 extends downwardlyinto the ladle 12 for conveying the mixture from the outlet pipe 6 intothe ladle. The upper end of the pipe 21 is guided about the exterior ofthe outlet pipe 6 so that it can be displaced axially upwardly from theposition shown in FIG. 4 in a telescopic manner passing over the outersurface of the outlet pipe. The guide sleeve which directs thetelescopic movement of the pipe 21 over the outlet pipe consists of acylindrical sleeve 22 secured to the upper end of the pipe 21 and havinga diameter slightly greater than the outside diameter of the outlet pipe6. Guide rails 23 are spaced about the outlet pipe 6 within the sleeve22 for effecting the axial sliding movement of the pipe over the outletpipe. The guide rails 23 are angularly spaced apart forming passagewaysbetween the sleeve 22 and the outer surface of the outlet pipe 6 forpermitting discharge of vapors. At the upper end of the sleeve 22, anannular shaped plate 24 extends radially outwardly forming a'support forthe combination of the sleeve 22 and the pipe 21. A lower hook 25 and anupper hook 26 extend downwardly from the lower surface of the vessel 3and provide means for engaging the surface of the plate 24 for holdingthe pipe 21 at the lower and upper limits of its telescopic travel overthe outlet pipe 6. In other words, when the pipe is at its lowestposition within the ladle 12 the plate 24 is supported on the hook 25,as is indicated in FIG. 4. When the pipe 21 moves upwardly over theoutlet pipe 6 it is supported in its upper position by the plate 24resting on the hook 26. At the lower end of the pipe 21 about itsexterior surface a float 27 of a refractory material is provided, therefractory material being selected for its buoyancy so that as the endof the pipe is immersed in the molten metal within the ladle 12 thefloat 27 causes the pipe 21 to move upwardly as the level of the moltenmaterial within the ladle 12 rises. The float will continue to lift thepipe upwardly until it reaches the maximum level of the molten metalwithin the ladle 12 at which time the plate 24 supports the sleeve 22and pipe 21 on the upper hook 26.

V 1 Another distinguishing characteristic of the arrangement in FIG. 4as compared to that in FIG. 1 is the construction of the shown anddescribed in detail to illustrate the application of the inventiveprinciples, it will be understood that the invention may be embodiedotherwise without departing from such principles.

What is claimed is:

1. In a device for introducing additives, in particular solid substancesof low boiling point, into a molten metal, comprising an intermediatevessel arranged to receive a supply of molten metal and having an outletopening in its base for discharging molten metal therefrom, and avertically positioned feed pipe for introducing additives into themolten metal, extending downwardly into the intermediate vessel, theimprovement comprising said outlet opening having an inner peripheralsurface; the lower end of said feed pipe extending through said outletopening with the outer surface of said feed pipe in spaced relation tothe inner peripheral surface of said outlet opening; means, includingthe outer surface of said feed pipe, the inner peripheral surface ofsaid outlet opening, and angularly spaced axially elongated radial ribs,dividing the flow area through said outlet opening into a plurality ofangularly spaced separated flow passages; and an outlet pipe extendingdownwardly from said outlet opening with its upper end in communicationwith said flow passages and with said feed pipe.

2. A device, as set forth in claim 1, wherein said dutl et pipe has itsinner surface converging inwardly for a portion of its length from theoutlet opening from said intermediate vessel. 3. A device, as set forthin claim 2, wherein a plurality of protuberances are formed on the innersurface of said outlet pipe within the zone of its inwardly convergingsurfaces, said protuberances being positioned between said ribs in saidoutlet pipe and said protuberances extending normally to the axis ofsaid outlet pipe. 7 u V v 4. A device, as set forth in clairn 2, whereinthe inner surface of said outlet pipe forms a short cylindrical sectionextending downwardly from the lower end of said inwardly convergingsection of said pipe.

5. A device, as set forth in claim 4, wherein the inner surface of saidoutlet pipe diverges outwardly from the lower end of said cylindricalsection in a nozzle-like form.

6. A device, as set forth in claim 5, wherein said outlet pipe has asecond converging section extending downwardly from the lower end ofsaid diverging section, a second cylindrical section extendingdownwardly from the lower end of said second converging section and asecond diverging section extending downwardly from the lower end of saidcylindrical section, and the cross sectional opening through said secondcylindrical section being less than the cross sectional opening throughsaid first cylindrical section of said outlet pipe.

7. A device, as set forth in claim 1, wherein a proportioning fiinnel isarranged at the upper end of said feed pipe for conveying additives intosaid feed pipe for flow downwardly therethrough into said outlet pipe.

8. A device for introducing additives, in particular solid substances oflow boiling point, into a molten metal is comprised of an intermediatevessel arranged to receive a supply of 5101- ten metal, saidintermediate vessel having an outlet opening in the base thereof fordischarging molten metal therefrom, a vertically positioned feed pipefor introducing additives into the molten metal extending downwardlyinto said intermediate vessel, wherein the improvement comprises saidfeed pipe having its lower outlet end positioned within the outletopening from said intermediate vessel and having its outer surfacedisposed in spaced relationship from the surface of the outlet openingforming an annular space therebetween, a plurality of angularly spacedribs positioned within the annular space and extending between theoutlet end of said feed pipe and the surface of the outlet opening insaid intermediate vessel for dividing the annular space into a pluralityof open sections, and an outlet pipe connected to and extendingdownwardly from the outlet opening in said intermediate vessel forconveying molten metal from said intermediate vessel and additivesintroduced through said feed pipe; said ribs extending downwardly fromsaid outlet opening into said outlet pipe and extending through saidoutlet pipe for at least a portion of the length thereof.

9. A device for introducing additives, in particular solid substances oflow boiling point, into a molten metal is comprised of an intermediatevessel arranged to receive a supply of molten metal, said intermediatevessel having an outlet opening in the base thereof for dischargingmolten metal therefrom, a vertically positioned feed pipe forintroducing additives into the molten metal extending downwardly intosaid intermediate vessel, wherein the improvement comprises said feedpipe having its lower outlet end positioned within the outlet openingfrom said intermediate vessel and having its outer surface disposed inspaced relationship from the surface of the outlet opening forming anannular space therebetween, a plurality of angularly spaced ribspositioned within the annular space and extending between the outlet endof said feed pipe and the surface of the outlet opening in saidintermediate vessel for dividing the annular space into a plurality ofopen sections, and an outlet pipe connected to and extending downwardlyfrom the outlet opening in said intermediate vessel for conveying moltenmetal from said intermediate vessel and additives introduced throughsaid feed pipe; said ribs extending downwardly from said outlet openinginto said outlet pipe and extending through said outlet pipe for atleast a portion of the length thereof; said outlet pipe having its innersurface converging inwardly for a portion of its length from the outletopening from said intermediate vessel; the inner surface of said outletpipe forming a short cylindrical section extending downwardly from thelower end of said inwardly converging section of said pipe, anddiverging outwardly from the lower end of said cylindrical section in anozzle-like form; said ribs extending downwardly from the outlet openingin said intel-mediate vessel through the converging section andcylindrical section of said outlet pipe into the diverging section ofsaid outlet pipe, and said ribs terminating at a point spaced from theoutlet end of said diverging section.

10. A device for introducing additives, in particular solid substancesof low boiling point, into a molten metal is comprised of anintermediate vessel arranged to receive a supply of molten metal, saidintermediate vessel having an outlet opening in the base thereof fordischarging molten metal therefrom, a vertically positioned feed pipefor inroducing additives into the molten metal extending downwardly intosaid intermediate vessel, wherein the improvement comprises said feedpipe having its lower outlet end positioned within the outlet openingfrom said intermediate vessel and having its outer surface disposed inspaced relationship from the surface of the outlet opening forming anannular space therebetween, a plurality of angularly spaced ribspositioned within the annular space and extending between the outlet endof said feed pipe and the surface of the outlet opening in saidintermediate vessel for dividing the annular space into a plufality of 63; sections, and an outlet pipe connected to and extending downwardlyfrom the outlet opening in said intermediate vessel for conveying moltenmetal from said intermediate vessel and additives introduced throughsaid feed pipe; a telescopically arranged refractory lined pipepositioned about said outlet pipe and arranged to extend downwardly fromthe lower end of said outlet pipe enclosing the flow of materials fromsaid outlet pipe into a vessel, and means for displacing said pipe intelescopic fashion over the exterior surface of said outlet pipe.

1 1. A device, as set forth in claim 10, wherein a guide sleeve issecured to and extends axially upwardly from the upper end of saidrefractory lined pipe, said guide sleeve having an inside diameterslightly larger than the outside diameter of said outlet pipe,vertically extending guide rails secured to the interior surface of saidsleeve and contacting the outer surface of said outlet pipe for guidingsaid refractory lined pipe upwardly over said outlet pipe, a refractoryfloat formed about the exterior surface of the lower end of saidrefractory lined pipe and the refractory material of said float having abuoyancy for lifting said refractory lined pipe as the level of moltenmetal rises within a vessel within which said refractory lined pipe ispositioned.

12. A device, as set forth in claim 11, wherein an annular plate issecured to and extends outwardly from the upper end of said guidesleeve, a lower hook secured to and extending downwardly from saidintermediate vessel to a point spaced above the outlet end of saidoutlet pipe, an upper hook secured to the lower surface of saidintermediate vessel and positioned adjacent the lower surface of saidintermediate vessel, said lower hook and said upper hook arranged toengage said annular plate for supporting said refractory lined pipe atthe lower limit and the upper limit of its travel relative to saidoutlet pipe.

13. A device for introducing additives, in particular solid substancesof low boiling point, into a molten metal is comprised of anintermediate vessel arranged to receive a supply of molten metal, saidintermediate vessel having an outlet opening in the base thereof fordischarging molten metal therefrom, a vertically positioned feed pipefor introducing additives into the molten metal extending downwardlyinto said intermediate vessel, wherein the improvement comprises saidfeed pipe having its lower outlet end positioned within the outletopening from said intermediate vessel and having its outer surfacedisposed in spaced relationship from the surface of the outlet openingforming an annular space therebetween, a plurality of angularly spacedribs positioned within the annular space and extending between theoutlet end of said feed pipe and the surface of the outlet opening insaid intermediate vessel for dividing the annular space into a pluralityof open sections, and an outlet pipe connected to and extendingdownwardly from the outlet opening in said intermediate vessel forconveying molten metal from said intermediate vessel and additivesintroduced through said feed pipe; a second vessel located below andarranged to receive molten material and additives from the lower end ofsaid outlet pipe, and a siphontype component formed in said secondvessel and having a tubular passage in alignment with said outlet pipefor receiving the mixture of molten metal and additives from said outletpipe and for introducing the mixture of molten metal and additives intothe base of said second vessel with the outlet from said siphon-typecomponent being located at a level above the bottom of said secondvessel.

14. A device, as set forth in claim 13, wherein said siphontypecomponent comprises a tubular section formed in the wall of said secondvessel and secured at its upper end to the lower outlet end of saidoutlet pipe and extending downwardly to a point spaced upwardly from thebase of said second vessel, a basin formed in the lower end of saidsecond vessel aligned below said tubular section for receiving themixture of molten material and additives therefrom, said basin having anupper edge over which the mixture of molten material and additives flowsfrom said basin into the remainder of said second vessel and the upperedge of said basin being disposed upw afilyabove the lower edge ofsaidtubular section Sofia? the lower end of said tubular section isclosed from access to air when said basin is filled with the mixture ofmolten materials and additives.

15. A device for introducing additives, in particular solid substancesof low boiling point, into a molten metal is comprised of anintermediate vessel arranged to receive a supply of molten metal, saidintermediate vessel having an outlet opening in the base thereof fordischarging molten metal therefrom, a vertically positioned feed pipefor introducing additives into the molten metal extending downwardlyinto said intermediate vessel, wherein the improvement comprises saidfeed pipe having its lower outlet end positioned within the outletopening from said intermediate vessel and having its outer surfacedisposed in spaced relationship from the surface; of the outlet openingforming an annular space therebetween, a plurality of angularly spacedribs positioned within the annular space and extending between theoutlet end of said feed pipe and the surface of the outlet opening insaid intermediate vessel for dividing the annular space into a pluralityof open sections, and an outlet pipe connected to and extendingdownwardly from the outlet opening in said intermediate vessel forconveying molten metal from said intermediate vessel and additivesintroduced through said feed pipe; said feed pipe comprising an innerpipe and a concentrically arranged outer pipe spaced outwardly from theouter surface of said inner pipe providing an annular spacetherebetween, said inner pipe and said outer pipe extending downwardlyto the outlet opening from said intermediate vessel.

16. A device, as set forth in claim 15, wherein a proportioning funnelspaced above the inlet opening to said inner pipe for supplying additivesubstances thereto, a concentrically arranged outer funnel extendingabout said proportioning funnel and secured at its lower end to theupper end of said inner pipe whereby vapors formed within said outletpipe can pass upwardly in the annular space between said inner pipe andsaid outer pipe flowing outwardly from the upper end of the annu larspace about said outer funnel so that the vapors cannot pass downwardlyinto the inner pipe with said additive substances.

17. A device for introducing additives, in particular solid substancesof low boiling point, into a molten metal is comprised of anintermediate vessel arranged to receive a supply of molten metal, saidintermediate vessel having an outlet opening in the base thereof fordischarging molten metal therefrom, a vertically positioned feed pipefor introducing additives into the molten metal extending downwardlyinto said intermediate vessel, wherein the improvement comprises saidfeed pipe having its lower outlet end positioned within the outletopening from said intermediate vessel and having its outer surfacedisposed in spaced relationship from the surface of the outlet openingforming an annular space therebetween, a plurality of angularly spacedribs positioned within the annular space and extending between theoutlet end of said feed pipe and the surface of the outlet opening insaid intermediate vessel for dividing the annular space into a pluralityof open sections, and an outlet pipe connected to and extendingdownwardly from the outlet opening in said intermediate vessel forconveying molten metal from said intermediate vessel and additivesintroduced through said feed pipe; a proportioning funnel extendingdownwardly into the upper end of said feed pipe for supplying additivesubstances thereto, said ribs extending downwardly from the outletopening from said intermediate vessel into said outlet pipe for at leasta portion of the length thereof, said outlet pipe having a convergingsection extending downwardly from the outlet opening from saidintermediate vessel for a portion of its length, said outlet pipe havinga cylindrical section extending downwardly from the lower end of saidconverging section and said outlet pipe having a diverging sectionextending downwardly from the lower end of said cylindrical section tothe outlet opening from said outlet pipe, a second vessel being locatedat the outlet end of said outlet pipe and arranged to receive themixture of molten metal and additives from said outlet pipe, said secondvessel comprising a siphon-type component arranged to receive themixture of molten metal and additives from said outlet pipe forconveying the mixture into the lower end of said vessel, saidsiphon-type component comprising a tubular section formed in the wall ofsaid second vessel and extending downwardly to a level above the bottomof said second vessel, a basin arranged below said tubular section forreceiving the mixture from said tubular section and for conveying themixture into said second vessel, said basin having an upper edge overwhich the mixture flows into said second vessel and the upper edge ofsaid basin being located vertically upwardly above the lower end of saidtubular section for preventing the passage of air into said tubularsection; when said basin is filled with the mixture of molten materialand additives.

18. A device for introducing additives, in particular solid substancesof low boiling point, into a molten metal is com prised of anintermediate vessel arranged to receive a supply of molten metal, saidintermediate vessel having an outlet opening in the base thereof fordischarging molten metal therefrom, a vertically positioned feed pipefor introducing additives into the molten metal extending downwardlyinto said intermediate vessel, wherein the improvement comprisessaidfeed pipe having its lower outlet end positioned within the outletopening from said intermediate vessel and having its outer surfacedisposed in spaced relationship from the surface of the outlet openingforming an annular space therebetween, a plurality of angularly spacedribs positioned within the annular space and extending between theoutlet end of said feed pipe and the surface of the outlet opening insaid intermediate vessel for dividing the annular space into a pluralityof open sections, and an outlet pipe connected to and extendingdownwardly from the outlet opening in said intermediate vessel forconveying molten metal from said intermediate vessel and additivesintroduced through said feed pipe; a feed means located above said feedpipe for introducing a rod type material downwardly into said feed pipefor admission into said outlet pipe, said outlet pipe comprising inserial arrangement from the outlet opening in said intermediate vesselto the outlet opening from said outlet pipe a converging section, acylindrical section, a diverging section, a second converging sec tion,a second cylindrical section, a second diverging section terminating inthe outlet end of said outlet pipe, the cross-sectional size of saidsecond cylindrical section being smaller than the cross-sectional sizeof said cylindrical section of said outlet pipe, said ribs extendingdownwardly through said outlet pipe from said outlet opening from saidintermediate vessel into a location intermediate the ends of saiddiverging section, a second vessel arranged below the lower end of saidoutlet pipe for receiving the mixture of molten material and additivesfrom said outlet pipe, a telescopically arranged refractorylined pipepositioned to extend from the lower end of said outlet pipe into saidsecond vessel, means for telescopically guiding said refractory-linedpipe over the exterior surface of said outlet pipe, said meanscomprising a guide sleeve secured to the upper end of saidrefractory-lined pipe and said guide sleeve having a diameter slightlygreater than the diameter of the outside of said outlet pipe, guidemembers positioned within said guide sleeve and extending between saidguide sleeve and the outer surface of said outlet pipe for guiding thetelescopic movement of said refractory-lined pipe therealong, said guidemembers angularly spaced apart within said guide sleeve for providingpassages therebetween for conveying vapors upwardly from saidrefractory-fined pipe to the exterior of said outlet pipe, a floatformed of a refractory material secured to the exterior lower end ofsaid refractory-lined pipe, the refractory material of said float beingarranged to lift said refractory-lined pipe in a telescopic manner oversaid outlet pipe as the level of molten material rises within saidsecond vessel, and a lower hook means secured to and extendingdownwardly from the lower end of said intermediate vessel to a positionspaced above the lower end of said outlet pipe, an upper hook secured tothe lower surface of said intermediate pipe and above said lower hook,an annular plate secured to and extending radially outwardly min" melTpper end of said said refractory-lined pipe as it passestelescopically over said guide sleeve and arranged to engage said lowerhook and said outlet pipe.

upper hook for defining the lower and upper limits of travel of

1. In a device for introducing additives, in particular solid substances of low boiling point, into a molten metal, comprising an intermediate vessel arranged to receive a supply of molten metal and having an outlet opening in its base for discharging molten metal therefrom, and a vertically positioned feed pipe for introducing additives into the molten metal, extending downwardly into the intermediate vessel, the improvement comprising said outlet opening having an inner peripheral surface; the lower end of said feed pipe extending through said outlet opening with the outer surface of said feed pipe in spaced relation to the inner peripheral surface of said outlet opening; means, including the outer surface of said feed pipe, the inner peripheral surface of said outlet opening, and angularly spaced axially elongated radial ribs, dividing the flow area through said outlet opening into a plurality of angularly spaced separated flow passages; and an outlet pipe extending downwardly from said outlet opening with its upper end in communication with said flow passages and with said feed pipe.
 2. A device, as set forth in claim 1, wherein said outlet pipe has its inner surface converging inwardly for a portion of its length from the outlet opening from said intermediate vessel.
 3. A device, as set forth in claim 2, wherein a plurality of protuberances are formed on the inner surface of said outlet pipe within the zone of its inwardly converging surfaces, said protuberances being positioned between said ribs in said outlet pipe and said protuberances extending normally to the axis of said outlet pipe.
 4. A device, as set forth in claim 2, wherein the inner surface of said outlet pipe forms a short cylindrical section extending downwardly from the lower end of said inwardly converging section of said pipe.
 5. A device, as set forth in claim 4, wherein the inner surface of said outlet pipe diverges outwardly from the lower end of said cylindrical section in a nozzle-like form.
 6. A device, as set forth in claim 5, wherein said outlet pipe has a second converging section extending downwardly from the lower end of said diverging section, a second cylindrical section extending downwardly from the lower end of said second converging section and a second diverging section extending downwardly from the lower end of said cylindrical section, and the cross sectional opening through said second cylindrical section being less than the cross sectional opening through said first cylindrical section of said outlet pipe.
 7. A device, as set forth in claim 1, wherein a proportioning funnel is arranged at the upper end of said feed pipe for conveying additives into said feed pipe for flow downwardly therethrough into said outlet pipe.
 8. A device for introducing additives, in particular solid substances of low boiling point, into a molten metal is comprised of an intermediate vessel arranged to receive a supply of molten metal, said intermediate vessel having an outlet opening in the base thereof for discharging molten metal therefrom, a vertically positioned feed pipe for introducing additives into the molten metal extending downwardly into said intermediate vessel, wherein the improvement comprises said feed pipe having its lower outlet end positioned within the outlet opening from said intermediate vessel and having its outer surface disposed in spaced relationship from the surface of the outlet opening forming an annular space therebetween, a plurality of angularly spaced ribs positioned within the annular space and extending between the outlet end of said feed pipe and the surface of the outlet opening in said intermediate vessel for dividing the annular space into a plurality of open sections, and an outlet pipe connected to and extending downwardly from the outlet opening in said intermediate vessel for conveying molten metal from said intermediate vessel and addiTives introduced through said feed pipe; said ribs extending downwardly from said outlet opening into said outlet pipe and extending through said outlet pipe for at least a portion of the length thereof.
 9. A device for introducing additives, in particular solid substances of low boiling point, into a molten metal is comprised of an intermediate vessel arranged to receive a supply of molten metal, said intermediate vessel having an outlet opening in the base thereof for discharging molten metal therefrom, a vertically positioned feed pipe for introducing additives into the molten metal extending downwardly into said intermediate vessel, wherein the improvement comprises said feed pipe having its lower outlet end positioned within the outlet opening from said intermediate vessel and having its outer surface disposed in spaced relationship from the surface of the outlet opening forming an annular space therebetween, a plurality of angularly spaced ribs positioned within the annular space and extending between the outlet end of said feed pipe and the surface of the outlet opening in said intermediate vessel for dividing the annular space into a plurality of open sections, and an outlet pipe connected to and extending downwardly from the outlet opening in said intermediate vessel for conveying molten metal from said intermediate vessel and additives introduced through said feed pipe; said ribs extending downwardly from said outlet opening into said outlet pipe and extending through said outlet pipe for at least a portion of the length thereof; said outlet pipe having its inner surface converging inwardly for a portion of its length from the outlet opening from said intermediate vessel; the inner surface of said outlet pipe forming a short cylindrical section extending downwardly from the lower end of said inwardly converging section of said pipe, and diverging outwardly from the lower end of said cylindrical section in a nozzle-like form; said ribs extending downwardly from the outlet opening in said intermediate vessel through the converging section and cylindrical section of said outlet pipe into the diverging section of said outlet pipe, and said ribs terminating at a point spaced from the outlet end of said diverging section.
 10. A device for introducing additives, in particular solid substances of low boiling point, into a molten metal is comprised of an intermediate vessel arranged to receive a supply of molten metal, said intermediate vessel having an outlet opening in the base thereof for discharging molten metal therefrom, a vertically positioned feed pipe for introducing additives into the molten metal extending downwardly into said intermediate vessel, wherein the improvement comprises said feed pipe having its lower outlet end positioned within the outlet opening from said intermediate vessel and having its outer surface disposed in spaced relationship from the surface of the outlet opening forming an annular space therebetween, a plurality of angularly spaced ribs positioned within the annular space and extending between the outlet end of said feed pipe and the surface of the outlet opening in said intermediate vessel for dividing the annular space into a plurality of open sections, and an outlet pipe connected to and extending downwardly from the outlet opening in said intermediate vessel for conveying molten metal from said intermediate vessel and additives introduced through said feed pipe; a telescopically arranged refractory lined pipe positioned about said outlet pipe and arranged to extend downwardly from the lower end of said outlet pipe enclosing the flow of materials from said outlet pipe into a vessel, and means for displacing said pipe in telescopic fashion over the exterior surface of said outlet pipe.
 11. A device, as set forth in claim 10, wherein a guide sleeve is secured to and extends axially upwardly from the upper end of said refractory lined pipe, said guide sleeve having an inside diameter slightly larger than the outside diametEr of said outlet pipe, vertically extending guide rails secured to the interior surface of said sleeve and contacting the outer surface of said outlet pipe for guiding said refractory lined pipe upwardly over said outlet pipe, a refractory float formed about the exterior surface of the lower end of said refractory lined pipe and the refractory material of said float having a buoyancy for lifting said refractory lined pipe as the level of molten metal rises within a vessel within which said refractory lined pipe is positioned.
 12. A device, as set forth in claim 11, wherein an annular plate is secured to and extends outwardly from the upper end of said guide sleeve, a lower hook secured to and extending downwardly from said intermediate vessel to a point spaced above the outlet end of said outlet pipe, an upper hook secured to the lower surface of said intermediate vessel and positioned adjacent the lower surface of said intermediate vessel, said lower hook and said upper hook arranged to engage said annular plate for supporting said refractory lined pipe at the lower limit and the upper limit of its travel relative to said outlet pipe.
 13. A device for introducing additives, in particular solid substances of low boiling point, into a molten metal is comprised of an intermediate vessel arranged to receive a supply of molten metal, said intermediate vessel having an outlet opening in the base thereof for discharging molten metal therefrom, a vertically positioned feed pipe for introducing additives into the molten metal extending downwardly into said intermediate vessel, wherein the improvement comprises said feed pipe having its lower outlet end positioned within the outlet opening from said intermediate vessel and having its outer surface disposed in spaced relationship from the surface of the outlet opening forming an annular space therebetween, a plurality of angularly spaced ribs positioned within the annular space and extending between the outlet end of said feed pipe and the surface of the outlet opening in said intermediate vessel for dividing the annular space into a plurality of open sections, and an outlet pipe connected to and extending downwardly from the outlet opening in said intermediate vessel for conveying molten metal from said intermediate vessel and additives introduced through said feed pipe; a second vessel located below and arranged to receive molten material and additives from the lower end of said outlet pipe, and a siphon-type component formed in said second vessel and having a tubular passage in alignment with said outlet pipe for receiving the mixture of molten metal and additives from said outlet pipe and for introducing the mixture of molten metal and additives into the base of said second vessel with the outlet from said siphon-type component being located at a level above the bottom of said second vessel.
 14. A device, as set forth in claim 13, wherein said siphon-type component comprises a tubular section formed in the wall of said second vessel and secured at its upper end to the lower outlet end of said outlet pipe and extending downwardly to a point spaced upwardly from the base of said second vessel, a basin formed in the lower end of said second vessel aligned below said tubular section for receiving the mixture of molten material and additives therefrom, said basin having an upper edge over which the mixture of molten material and additives flows from said basin into the remainder of said second vessel and the upper edge of said basin being disposed upwardly above the lower edge of said tubular section so that the lower end of said tubular section is closed from access to air when said basin is filled with the mixture of molten materials and additives.
 15. A device for introducing additives, in particular solid substances of low boiling point, into a molten metal is comprised of an intermediate vessel arranged to receive a supply of molten metal, said intermediate vessel having an outlet opening in the base thereof foR discharging molten metal therefrom, a vertically positioned feed pipe for introducing additives into the molten metal extending downwardly into said intermediate vessel, wherein the improvement comprises said feed pipe having its lower outlet end positioned within the outlet opening from said intermediate vessel and having its outer surface disposed in spaced relationship from the surface of the outlet opening forming an annular space therebetween, a plurality of angularly spaced ribs positioned within the annular space and extending between the outlet end of said feed pipe and the surface of the outlet opening in said intermediate vessel for dividing the annular space into a plurality of open sections, and an outlet pipe connected to and extending downwardly from the outlet opening in said intermediate vessel for conveying molten metal from said intermediate vessel and additives introduced through said feed pipe; said feed pipe comprising an inner pipe and a concentrically arranged outer pipe spaced outwardly from the outer surface of said inner pipe providing an annular space therebetween, said inner pipe and said outer pipe extending downwardly to the outlet opening from said intermediate vessel.
 16. A device, as set forth in claim 15, wherein a proportioning funnel spaced above the inlet opening to said inner pipe for supplying additive substances thereto, a concentrically arranged outer funnel extending about said proportioning funnel and secured at its lower end to the upper end of said inner pipe whereby vapors formed within said outlet pipe can pass upwardly in the annular space between said inner pipe and said outer pipe flowing outwardly from the upper end of the annular space about said outer funnel so that the vapors cannot pass downwardly into the inner pipe with said additive substances.
 17. A device for introducing additives, in particular solid substances of low boiling point, into a molten metal is comprised of an intermediate vessel arranged to receive a supply of molten metal, said intermediate vessel having an outlet opening in the base thereof for discharging molten metal therefrom, a vertically positioned feed pipe for introducing additives into the molten metal extending downwardly into said intermediate vessel, wherein the improvement comprises said feed pipe having its lower outlet end positioned within the outlet opening from said intermediate vessel and having its outer surface disposed in spaced relationship from the surface of the outlet opening forming an annular space therebetween, a plurality of angularly spaced ribs positioned within the annular space and extending between the outlet end of said feed pipe and the surface of the outlet opening in said intermediate vessel for dividing the annular space into a plurality of open sections, and an outlet pipe connected to and extending downwardly from the outlet opening in said intermediate vessel for conveying molten metal from said intermediate vessel and additives introduced through said feed pipe; a proportioning funnel extending downwardly into the upper end of said feed pipe for supplying additive substances thereto, said ribs extending downwardly from the outlet opening from said intermediate vessel into said outlet pipe for at least a portion of the length thereof, said outlet pipe having a converging section extending downwardly from the outlet opening from said intermediate vessel for a portion of its length, said outlet pipe having a cylindrical section extending downwardly from the lower end of said converging section and said outlet pipe having a diverging section extending downwardly from the lower end of said cylindrical section to the outlet opening from said outlet pipe, a second vessel being located at the outlet end of said outlet pipe and arranged to receive the mixture of molten metal and additives from said outlet pipe, said second vessel comprising a siphon-type component arranged to receive the mixture of molten metal and additives from said outlet pipe for conveying the mixture into the lower end of said vessel, said siphon-type component comprising a tubular section formed in the wall of said second vessel and extending downwardly to a level above the bottom of said second vessel, a basin arranged below said tubular section for receiving the mixture from said tubular section and for conveying the mixture into said second vessel, said basin having an upper edge over which the mixture flows into said second vessel and the upper edge of said basin being located vertically upwardly above the lower end of said tubular section for preventing the passage of air into said tubular section when said basin is filled with the mixture of molten material and additives.
 18. A device for introducing additives, in particular solid substances of low boiling point, into a molten metal is comprised of an intermediate vessel arranged to receive a supply of molten metal, said intermediate vessel having an outlet opening in the base thereof for discharging molten metal therefrom, a vertically positioned feed pipe for introducing additives into the molten metal extending downwardly into said intermediate vessel, wherein the improvement comprises said feed pipe having its lower outlet end positioned within the outlet opening from said intermediate vessel and having its outer surface disposed in spaced relationship from the surface of the outlet opening forming an annular space therebetween, a plurality of angularly spaced ribs positioned within the annular space and extending between the outlet end of said feed pipe and the surface of the outlet opening in said intermediate vessel for dividing the annular space into a plurality of open sections, and an outlet pipe connected to and extending downwardly from the outlet opening in said intermediate vessel for conveying molten metal from said intermediate vessel and additives introduced through said feed pipe; a feed means located above said feed pipe for introducing a rod type material downwardly into said feed pipe for admission into said outlet pipe, said outlet pipe comprising in serial arrangement from the outlet opening in said intermediate vessel to the outlet opening from said outlet pipe a converging section, a cylindrical section, a diverging section, a second converging section, a second cylindrical section, a second diverging section terminating in the outlet end of said outlet pipe, the cross-sectional size of said second cylindrical section being smaller than the cross-sectional size of said cylindrical section of said outlet pipe, said ribs extending downwardly through said outlet pipe from said outlet opening from said intermediate vessel into a location intermediate the ends of said diverging section, a second vessel arranged below the lower end of said outlet pipe for receiving the mixture of molten material and additives from said outlet pipe, a telescopically arranged refractory-lined pipe positioned to extend from the lower end of said outlet pipe into said second vessel, means for telescopically guiding said refractory-lined pipe over the exterior surface of said outlet pipe, said means comprising a guide sleeve secured to the upper end of said refractory-lined pipe and said guide sleeve having a diameter slightly greater than the diameter of the outside of said outlet pipe, guide members positioned within said guide sleeve and extending between said guide sleeve and the outer surface of said outlet pipe for guiding the telescopic movement of said refractory-lined pipe therealong, said guide members angularly spaced apart within said guide sleeve for providing passages therebetween for conveying vapors upwardly from said refractory-lined pipe to the exterior of said outlet pipe, a float formed of a refractory material secured to the exterior lower end of said refractory-lined pipe, the refractory material of said float being arranged to lift said refractory-lined pipe in a telescopic manner over said outlet pipe as the level of molten material rises within said second vessel, and a lower Hook means secured to and extending downwardly from the lower end of said intermediate vessel to a position spaced above the lower end of said outlet pipe, an upper hook secured to the lower surface of said intermediate vessel and positioned adjacent the upper end of said outlet pipe and above said lower hook, an annular plate secured to and extending radially outwardly from the upper end of said guide sleeve and arranged to engage said lower hook and said upper hook for defining the lower and upper limits of travel of said refractory-lined pipe as it passes telescopically over said outlet pipe. 